(a) Field of the Invention
The present invention relates to a document management system and, more particularly, to a document management system for handling the attest data for authorizing electronic documents in a computer system.
(b) Description of a Related Art
There have been increasing demands to make the image synthesizes a signature to an electronic document and to obtain the print output. A computer system using a network can be used as an open-ended and reliable system if the signature image data can be used in the computer system for authorizing the electronic document.
There is a prior art describing a signature image data unit and document data unit in a closed computer system, not used independently in network, and there is a problem in examining the correctness of a personal seal or signature (referred to as simply signature hereinafter).
For instance, Patent Publication JP-A-6-119363 describes such a document management system. The described system includes a document data storage unit for storing created electronic documents, a signature image data storage unit for storing the signature image data in association with the signer ID number, (two units being integrated in a same computer system), a protective attribute generator for attaching a protective attribute for protecting the documents stored in the document data storage unit by prohibiting the change of the documents, an attest information generator for attaching attest information including signer ID number to the electronic document stored in the document data storage unit in response to the operation by the operator or thereby allow the protective attribute generator to attach the protective attribute to the electronic document, and a signal processor for reading, based on the signer ID number, the electronic document stored in the document data storage unit and attached with the attest information and the protective attribute to synthesize the image data stored in the signature image data storage unit corresponding to the signer ID number onto the electronic document and output the same to an output unit. In the output, document data and the signature image are printed, the signer ID number is not printed.
In the described system, it is recited that the system stores beforehand a signature image data for authorizing the electronic document created by a word processor or electronic mail and delivers the document data after synthesizing the document data with the signature image data. It is also recited that the electronic document is protected from an unauthorized approval or a wrong change thereof after the authorization by attaching the attest information to the electronic document, whereby an unqualified person is prohibited from illegal authorization or willful change of the electronic document by a criminal or illegal deed.
In the described system, however, there is a problem in that it is difficult in fact to judge the correctness of the signature image due to the ambiguity of the printed data of the signature image due to the of the sharpness of the printed matter and the signature image data storage unit is not independent of document data storage unit computer system, so it is difficult for the plural signers to access to the plural signature image data system in computer network independently and register signature images after the signer's secured approval, and attach those signature image data to the same document data individually.